In To Kill a Mockingbird, how does Atticus's dealings with different characters bring out different aspects of his own character?

In his treatment of others, Atticus reveals his own personal integrity. His actions confirm the values he professes, and how he interacts with the other characters in the novel reveals his decency, strength, and wisdom.

Atticus values truth and justice; he reveres the law. In taking Tom Robinson’s case and fighting so hard to free Tom from a gross injustice, Atticus lives his principles. After losing in court, Atticus plans to appeal Tom’s conviction; he...

In his treatment of others, Atticus reveals his own personal integrity. His actions confirm the values he professes, and how he interacts with the other characters in the novel reveals his decency, strength, and wisdom.

Atticus values truth and justice; he reveres the law. In taking Tom Robinson’s case and fighting so hard to free Tom from a gross injustice, Atticus lives his principles. After losing in court, Atticus plans to appeal Tom’s conviction; he will not abandon an innocent man. His gentle treatment of Tom and Tom’s family shows the compassion, empathy, and decency in Atticus’s character. These same personal traits are shown in his treatment of Mrs. Dubose. Despite her difficult behavior, Atticus understands her situation and her feelings and treats her with respect and consideration.

How Atticus interacts with his children demonstrates his great love for them and his wisdom in guiding them through difficult times. He listens to them, answers their questions as honestly as he can, and instills in them, through word and deed, core values of honesty, courage, fairness, respect, and compassion.

Finally, the manner in which Atticus deals with Bob Ewell also shows Atticus’s character. He abhors Ewell’s behavior, but he does not attack him personally or denigrate him while questioning him during Tom’s trial. He examines Ewell as a witness, asking the hard questions, but even Ewell is treated with respect while on the stand. Later, when Ewell confronts Atticus and spits in his face, Atticus does not react to the insult. His self-respect and dignity demand that he ignore Ewell’s ignorant and spiteful display.

When Atticus is dealing with Jem and Scout, he is the wise, all-knowing father, but he disciplines and reasons with them. He also treats them like they are adults, and often stops to teach them about morals and values. When Atticus is walking in town and Bob Ewell spits in his face, he refuses to fight, telling Bob that the reason he won't is because he is too old for that such thing. When he comes home and the children have found out, he brings humor to the situation, saying that he wished Bob Ewell didn't chew tobacco. Even though he is scared and worried for his children, the children never see that side of him. Scout tells us of his fear and worry when she is eavesdropping on his conversations with his brother and sister. Finally, the way in which Atticus treats Tom, and ultimately Tom's wife and children after Tom's death, reveals Atticus's compassion for others, and his honor. Just as he tells his children, a man needs to stand up for what he believes is right, even if he's the only one standing.

Atticus rarely shows changes in temperament or character during the course of the novel. As Miss Maudie tells Scout,

“Atticus Finch is the same in his house as he is on the public streets.”

Aside from his children, Atticus treats everyone equally. There are times, however, when the reader receives a different glimpse at his inner side. Miss Maudie tends to bring out his humorous side; he has a bit of fun with her when he discovers Scout aiming at Maudie's "generous" backside. Their neighbor retorts that Atticus is "a devil from hell." Atticus reverts to his most charming self when dealing with the cantankerous Mrs. Dubose, sweeping off his hat to "wave gallantly" followed by an exaggerated compliment. He has his arguments with sister Alexandra because they disagree on so many family matters. With his own children, Atticus shows even more patience and compassion than usual, alternating between firm but quiet guidance and tender compassion.